Radiator fan relay?

One more for the tech guys. Just did a ton of work under hood of 1989 TC 8 valve. Radiator fan motor runs fine with AC on, but only now and then on some days if not on, most days it won't run unless AC is on. Mechanic checked one relay and said it is working, but I read on this forum that there are two relays for Rad fan? Mechanic thinks engine control module needs to be checked? Any help or suggestions would be greatly appreciated. Thanks, Rick

One more for the tech guys. Just did a ton of work under hood of 1989 TC 8 valve. Radiator fan motor runs fine with AC on, but only now and then on some days if not on, most days it won't run unless AC is on. Mechanic checked one relay and said it is working, but I read on this forum that there are two relays for Rad fan? Mechanic thinks engine control module needs to be checked? Any help or suggestions would be greatly appreciated. Thanks, Rick

Have you waited long enough for the coolant to reach 212 degrees? It has to get to that temperature before the fan relay is energized. Has your temperature gauge ever gone up beyond 2/3 or have you noticed any overheating of the engine?

Thank you again, Mr. Hemi Dude! TC does not warm up very fast, but when it did that fan came right on. Spent a ton of money under the hood, car goes to paint Friday. Interior to be redone in a few months. I really need the help and info I get from this site and the newsletter. No one around here will work on this car because they don't know how. Luckily, I found an antique and classic mobile car mechanic that is very dependable and reasonable prices. We both are learning about this car as we go along and the help here is invaluable. Sorry about some of the dumb questions I have to ask. BTW, me and my TC will be participating in the 2014 "Cruisin The Coast" in Biloxi Ms. from October 6 to October 12. I have not seen anyone mention this event on this site. This is the 18th annual Cruise, and last year around 8,000 cars registered for the event and about 13,000 cars showed up to cruise. My 1989 TC 8 valve, Red and Ginger will be in the big parade on Monday, October 6.

One way to test fan relays is just unplug the coolant temperature sensor if the fan's don't turn on immediately you have a problem somewhere else other than the relays. I'm new to the TC's but more years than I care to admit fooling with chrysler 2.2 Turbo powered stuff. Most of the time when a fan fails to turn on it is because it burned up a fuse-able link due to the cooling fan motor failing. Or a relay has hung up, and if you bang on it and they turn on it's time to replace the relay, but if they turn on with the ac it is like the previous poster stated it is usually due to a coolant temp sensor failure or just not being patient enough, assuming you have coolant in that area of the motor behind the thermostat. Which unless you bled the air out after a coolant flush won't be their. And air temperature (hot steam) won't turn on the fan's until the motor is cooked. So always verify you have bled the air out from behind the thermostat after a coolant change. The rest of the cooling system has always proved to be very reliable for me over the years. My father cooked a freshly rebuilt 2.6 years ago because of this.

Brett

Thank you again, Mr. Hemi Dude! TC does not warm up very fast, but when it did that fan came right on.

You may want to replace the thermostat in this case. Use a STANT HD 195 degree thermostat, I forget the number but parts store should be able to find it. ALSO, drill a small hole in what will be the top (upper) part of the thermostat when it is installed. This will aid in venting whatever air is remaining in the head when you add coolant to the system. Be sure to bleed as much air out as you can, then keep a close eye on the coolant and the dashboard temperature gauge as you let the engine warm up.

Initially leave the radiator cap off as the engine begins to warm so you can add coolant as the level drops the first time the thermostat begins to open, after that you need to keep the radiator cap ON the radiator as the engine warms up fully so any air ejected will dump in the coolant reservoir and only coolant can be drawn back in as the radiator fan cools the coolant in the first few fan on/off cycles. Add your coolant to the reservoir as needed during this time.

Here too, the radiator cap should be like the ORIGINAL cap was, that is, with the pressure 'check valve' free to hang open when the cap is on the radiator. DO NOT USE RADIATOR CAPS WITH SPRING LOADED 'CHECK VALVE' as this prevents the free flow of coolant to and from the reservoir. Most people end up replacing the correct original style cap with a "Lever Lock" cap or one with the spring loaded pressure check valve. EVERYONE, GET RID OF THAT SORT OF CAP, and get an original type. I suspect that this kind of radiator cap alone contributes the most to BLOWN HEAD GASKETS on the 2.2 & 2.5L engines. The cooling system should not run under 16 pounds pressure all the time, only in very hot conditions. Of course, you want at least a 50/50 mix of antifreeze/water in the system.

Edited September 26, 2014 by Hemi Dude
A little more addition to text. (see edit history)